Chapter 28 Exam 2 Flashcards
Human progress has always depended on expanding our use of plants for
Food
Fuel
Clothing
one of the most important agricultural products in the world today.
Coffee
Ground coffee is made from the ____ belonging to several species in the genus Coffea
seeds of plants
Coffee was discovered in Ethiopia during the
1200s
Coffee was discovered in __ during the 1200s.
Ethiopia
By the ____, coffee plants imported to the Americas were an important crop.
1700s
naturally produced by the coffee plant as a
self-defense against herbivores
Coffee does what
stimulates the nervous system
Plants are vital to the well-being of not just humans but the entire
biosphere
the flowering plants—make up more than 90% of the plant kingdom.
Angiosperms
Angiosperms make up more than __% of the plant kingdom.
90%
biologists who study plants
botanists
• On the basis of several structural differences, botanists (biologists who study plants) classify most angiosperms into two groups:
- Monocots
2. Eudicots
The names of the groups refer to embryonic structures called
cotyledons,
or seed leaves
the first leaves to emerge from a growing seedling.
cotyledons,
or seed leaves
Monocot embryo has
One seed leaf
Eudicot embryo has
Two seed leaves
many food crops (such as nearly all of our fruits and vegetables)
Eudicots
The majority of ornamental plants are
Eudicots
Most shrubs and trees (except for the gymnosperms)
Eudicots
consists of several types of tissues that together carry out a particular function. This includes roots, stems, leaves
Organs
an organ that
anchors a plant in the soil, absorbs and transports minerals and water, and stores food
Root
All of a plant’s roots make up its
root system
are tiny projections near the root tips
Root hairs
greatly increase the root surface area, providing an extensive outer layer for absorption of water and minerals.
Root hairs
found in carrots, turnips, sugar beets, and sweet potatoes
Large taproots
store food in the form of carbohydrates such as starch or sucrose.
Large taproots
______of a plant is made up of stems, leaves, flowers
shoot system
grow above the ground and support the flowers and leaves.
Stems
Has nodes and internodes
Stem
the points at which leaves are attached
Nodes
the portions of the stem between nodes.
Internodes
In many plants, the terminal bud produces hormones that inhibit growth of the axillary buds, a phenomenon called
apical dominance
Removing the terminal bud by pruning a fruit tree or “pinching back” a houseplant will make the plant
Bushier
has rhizomes ending in enlarged structures called tubers, where food is stored in the form of starch.
Potato
A potato plant has
Rhizomes
where food is stored in the form of starch.
Tubers
The ___ of a potato are axillary buds, which can grow into new plants, allowing potatoes to be easily propagated.
“eyes”
The “eyes” of a potato are
axillary buds
can grow into new plants, allowing potatoes to be easily propagated.
Axillary buds
the primary sites of photosynthesis in most plants
Leaves
This has a flattened blade and a stalk, or petiole
Leaf
joins the leaf to the stem
petiole
are groups of cells that together perform a specialized function.
Tissues
This tissue conveys water and dissolved minerals upward from the roots to the stems and leaves
Xylem
transports sugars from leaves or
storage tissues to other parts of the plant.
Phloem
consists of one or more tissues organized into a functional unit within a plant.
Tissue system
Each plant organ—is made up of three tissue systems:
the dermal,
vascular,
and ground tissue systems.
Each tissue system is continuous throughout the entire plant body, but the systems are ___
arranged differently in leaves, stems, and roots.
forms an outer protective covering
Dermal tissue system
forms a first line of defense against physical damage and infectious organisms
Dermal tissue system
On leaves and on most stems, dermal cells secrete a waxy coating
cuticle
which helps prevent water loss
the cuticle
provides support and long-distance transport
throughout the plant and includes xylem and phloem
Vascular tissue system
accounts for most of the bulk of a plant and has diverse functions, including photosynthesis, storage, support
The ground tissue system
- photosynthesis,
- storage,
- support.
Ground tissue system
where cells store food and take up water and minerals.
cortex
The innermost layer of cortex is the____, a thin cylinder one cell thick.
endodermis
a selective barrier that regulates the passage of substances between the cortex and the vascular tissue
endodermis
The epidermis contains __, tiny pores between two specialized _____,
stomata;
guard cells
which regulate the opening and closing of the stomata, allowing gas exchange between the surrounding air and photosynthetic cells inside the leaf
Guard cell
The main site of photosynthesis is the____, which is the ground tissue of a leaf.
mesophyll
The leaf’s vascular tissue system is made up of a ___
network of veins
The epidermis (the outer layer of the dermal system) is a single layer of tightly packed cells covering the entire root. ______from the soil enter the plant through these cells.
Water and minerals
cells that radiate from the center
Xylem
cells filling in the wedges between the spokes
Phloem
contains stomata, tiny pores between two specialized guard cells
Epidermis
Most plant cells have three unique structures
Chloroplasts
Central vacuole
Cell wall
are the sites of photosynthesis
Chloroplasts
A large _____ containing fluid helps
maintain the cell’s firmness
central vacuole
surrounds the plasma membrane and consists largely of the carbohydrate cellulose.
cell wall
the most abundant type of cell in most plants
Parenchyma cells
Have no secondary cell wall
Parenchyma cells
perform a variety of functions, such as food storage and photosynthesis
Parenchyma cells
can divide and differentiate into other types of plant cells, which they may do during repair of an injury.
parenchyma cells
Parenchyma cells can divide and differentiate into other types of plant cells, which they may do during
repair of an injury.
resemble parenchyma cells in lacking secondary walls, but they have unevenly thickened primary walls
Collenchyma cells
they have unevenly thickened primary walls which provide support in parts of the plant that are actively growing
Collenchyma
have thick secondary cell walls usually strengthened with lignin, the main chemical in wood.
Sclerenchyma cells
the main chemical in wood
Lignin
After they mature, most sclerenchyma cells__.
Die
After they mature, most sclerenchyma cells die. The rigid cell walls of these dead cells form a ____ that supports the plant.
Skeleton
The xylem tissue of angiosperms contains two types of ___.
water-conducting cells
contains two types of water-conducting cells. Both have rigid, lignin-containing secondary cell walls.
xylem tissue of angiosperms
The xylem tissue of angiosperms contains two types of water-conducting cells.
- Tracheids
2. Vessel elements
are long, thin cells with tapered ends
Tracheids
are wider, shorter, and less
tapered
Vessel elements
Chains of these make a ____ throughout plant
Tube
hollow as they are dead cells with just a
cell wall remaining.
Tubes
What passes through pits and ends of these tubes
Water
are also arranged end to end, forming tubes.
Food-conducting cells within phloem
Unlike water-conducting cells, however, food conducting cells within phloem cells remain alive at ____.
Maturity
Food conducting cells within phloem end walls, which are perforated with large ___
plasmodesmata
Food conducting cells within phloem allow ___to move between adjacent food-conducting cells.
sugars,
other compounds,
and some minerals
___ emerge from seed, mature, reproduce, and die in a single year or growing season.
Annuals
__ live for two years. Flowering and seed production usually occur during the second year.
Biennials
live and reproduce for many years.
Perennials
Growth in all plants is made possible by tissues called
meristems
undifferentiated (unspecialized) cells that divide when conditions permit, generating new cells and tissues
meristems
occur at the tips of roots and in the buds of shoots.
Apical meristems
Cell division in apical meristems produces new cells that enable a plant to grow in length, a process called __
primary growth
enables roots to push through soil
Primary growth
At the tip of the root is the ____
root cap
a thimble-like cone of DEAD cells that protects the delicate, actively dividing cells of the apical meristem
Root cap
The root’s apical meristem ____ of the root cap that are scraped away by the soil and produces cells for primary growth.
replaces cells
Primary growth is achieved by
cell division
lengthening of cells just above the apical meristem
In addition to lengthwise primary growth, the stems and roots of many eudicot species (but few monocots) also thicken by a process called
secondary growth
Such thickening in secondary growth is most evident in the
woody plants—trees, shrubs, and vines
whose stems last from year to year and consist mainly of thick layers of mature, mostly dead xylem tissue, called
Wood
Made mostly dead xylem tissue, called
Wood
a cylinder of actively dividing cells between the primary xylem and primary phloem.
vascular cambium
adds cells on either side of the vascular cambium
Secondary growth
Annual growth rings result from the layering of
secondary xylem
The layers are visible as rings because of ___ of the vascular cambium during the year
uneven activity
___ and __ make up the young stem’s external covering.
The epidermis and cortex
When secondary growth begins, the epidermis is shed and is replaced with a new outer layer called
cork
Cork cells die and leave ___
thick walls to protect the stem.
Cork is produced by a meristem tissue called the ___
cork cambium
Everything external to the vascular cambium (the secondary phloem, cork cambium, and cork) is called
bark
The bulk of a tree trunk is
Dead tissue
is secondary xylem and does NOT
conduct water any more. (Resin inside)
heartwood
consists of younger secondary xylem that does conduct water.
lighter-colored sapwood
As in animals, ____ in plants involves fertilization, the union of gametes from two parents to produce genetically distinct offspring.
sexual reproduction
enclose and protect the flower bud
Sepals
are often colorful and fragrant, which may serve to advertise the flower to insects and other pollinators
Petals
Stamen
Male or female?
MALE
Carpel
Male or female?
FEMALE
The flower’s reproductive organs are the
stamen and the carpel
stamen consists of a stalk tipped by
anther
Within the anther are sacs where ____ occurs and pollen grains develop.
Meiosis
Pollen grains house the cells that develop into ___
Sperm
has a long slender neck (the style) with a sticky stigma at its tip.
carpel
is the landing platform for pollen grains, acting like fly paper to which pollen sticks.
stigma
The base of the carpel is the ___.
ovary
Within the ovary are reproductive structures called
ovules
each containing one developing egg and the cells that support it
Ovules
The term is sometimes used to refer to a single carpel or a group of fused carpels.
pistil
After fertilization, the ovule of a flower matures into a seed containing the
embryo
Meanwhile, the ovary develops into a fruit, which
protects the seed and aids in dispersing it
Completing the life cycle of reproducing angiosperm
- the seed germinates (begins to grow),
- the embryo develops into a seedling,
- the seedling grows into a mature plant.
when each cell has a single
set of chromosomes
Abbreviated n
haploid generation
when each cell has two sets of
chromosomes, abbreviated 2n
Diploid generation
The roots, stems, leaves, and most of the
reproductive structures of angiosperms are
diploid
The diploid plant body, called a ____, produces the anthers in which cells undergo meiosis to produce haploid cells called spores.
sporophyte
The diploid plant body, called a sporophyte, produces the ___ in which cells undergo meiosis to produce haploid cells called spores.
anthers
diploid plant body, called a sporophyte, produces the anthers in which cells undergo meiosis to produce haploid cells called
spores
Fertilization requires gametes, which are produced by
gametophytes
The male gametophyte is the
Pollen grain
which is essential for pollination and produces sperm
Pollen grain
The female gametophyte is a multicellular structure called the
embryo sac
produces the egg
Embryo sac
The first step leading to fertilization is ___, the delivery of pollen grains from anther to stigma
pollination
Many angiosperms are dependent on who to transfer their pollen
insects,
birds,
other animals
But the pollen of some plants, such as grasses, is
wind-borne
After pollination, the pollen grain
germinates on the stigma
The pollen grain divides by
mitosis
forming two haploid sperm that travel to the ovule through a pollen tube that grows out from the pollen
Mitosis
occurs as one sperm fertilizes the egg, forming the diploid zygote
Double fertilization
other sperm in double fertilization
contributes its haploid nucleus to the large ____ central cell of the____
Diploid
embryo sac
The other sperm in double fertilization produces a triploid cell that will give rise to the food-storing tissue called
endosperm
Food storing tissue called
Endosperm
After fertilization, the ovule, containing the zygote and the triploid central cell, begins
developing into a seed
divides via mitosis and forms a ball of cells that becomes the embryo
Zygote
divides via mitosis and develops into the endosperm.
The triploid cell
The result of embryonic development in the ovule is a
mature seed
The result of embryonic development in the ovule is a mature seed, consisting of
A plant embryo
endosperm packaged within a tough protective
covering called a seed coat.
Seeds as old as ___ years (excavated from archaeological sites) can still sprout and form a new plant.
2,000
Seed dormancy is an important
Evolutionary adaptation
It allows time for seed dispersal and increases the chance that a new generation of plants will begin growing only when environmental conditions, such as temperature and moisture, favor their survival.
Seed dormancy
fruit is a mature ovary that acts as a __
vessel
housing and protecting seeds and helping disperse seeds from the parent plant
Fruit
Germination of a seed usually begins when the seed
takes up water
_____of a seed usually begins when the seed takes up water.
Germination
The hydrated seed expands, bursting its
Coat
The embryo then resumes the growth and development that were temporarily suspended during
seed dormancy
Most land animals depend on ____ for food and shelter.
angiosperms
The flowers of many angiosperms attract pollinators that rely entirely on the flowers’
nectar (a sugary fluid) and pollen for food
Bees pollinate $15 billion worth of crops each year, and an estimated ___ of our food supply relies on bees.
one-third
The cause of the die-off of bees has not yet been explained, although several possible causes have been proposed, including
- pesticides,
* various pathogens
yet another reminder of how much we all depend on plants for our survival.
Colony collapse disorder
Large taproots store food in the form of carbohydrates such as
starch or sucrose
